[Intel-gfx] [PATCH] drm/i915: Call drm_handle_vblank() after processing pending pageflips

[Chris Wilson]

When we process a pageflip completion, we append an event to the vblank
queue. That queue is processed by drm_handle_vblank() and so by calling
drm_handle_vblank() prior to processing the pageflips, we incur an extra
frame of latency in reporting the flip event.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_irq.c |   22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 6361276..e18e56b 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -564,13 +564,12 @@ static irqreturn_t valleyview_irq_handler(DRM_IRQ_ARGS)
 		spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
 
 		for_each_pipe(pipe) {
-			if (pipe_stats[pipe] & PIPE_VBLANK_INTERRUPT_STATUS)
-				drm_handle_vblank(dev, pipe);
-
 			if (pipe_stats[pipe] & PLANE_FLIPDONE_INT_STATUS_VLV) {
 				intel_prepare_page_flip(dev, pipe);
 				intel_finish_page_flip(dev, pipe);
 			}
+			if (pipe_stats[pipe] & PIPE_VBLANK_INTERRUPT_STATUS)
+				drm_handle_vblank(dev, pipe);
 		}
 
 		/* Consume port.  Then clear IIR or we'll miss events */
@@ -2220,22 +2219,22 @@ static irqreturn_t i8xx_irq_handler(DRM_IRQ_ARGS)
 		if (iir & I915_USER_INTERRUPT)
 			notify_ring(dev, &dev_priv->ring[RCS]);
 
-		if (pipe_stats[0] & PIPE_VBLANK_INTERRUPT_STATUS &&
-		    drm_handle_vblank(dev, 0)) {
+		if (pipe_stats[0] & PIPE_VBLANK_INTERRUPT_STATUS) {
 			if (iir & I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT) {
 				intel_prepare_page_flip(dev, 0);
 				intel_finish_page_flip(dev, 0);
 				flip_mask &= ~I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT;
 			}
+			drm_handle_vblank(dev, 0);
 		}
 
-		if (pipe_stats[1] & PIPE_VBLANK_INTERRUPT_STATUS &&
-		    drm_handle_vblank(dev, 1)) {
+		if (pipe_stats[1] & PIPE_VBLANK_INTERRUPT_STATUS) {
 			if (iir & I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT) {
 				intel_prepare_page_flip(dev, 1);
 				intel_finish_page_flip(dev, 1);
 				flip_mask &= ~I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT;
 			}
+			drm_handle_vblank(dev, 1);
 		}
 
 		iir = new_iir;
@@ -2418,13 +2417,13 @@ static irqreturn_t i915_irq_handler(DRM_IRQ_ARGS)
 			int plane = pipe;
 			if (IS_MOBILE(dev))
 				plane = !plane;
-			if (pipe_stats[pipe] & PIPE_VBLANK_INTERRUPT_STATUS &&
-			    drm_handle_vblank(dev, pipe)) {
+			if (pipe_stats[pipe] & PIPE_VBLANK_INTERRUPT_STATUS) {
 				if (iir & flip[plane]) {
 					intel_prepare_page_flip(dev, plane);
 					intel_finish_page_flip(dev, pipe);
 					flip_mask &= ~flip[plane];
 				}
+				drm_handle_vblank(dev, pipe);
 			}
 
 			if (pipe_stats[pipe] & PIPE_LEGACY_BLC_EVENT_STATUS)
@@ -2662,17 +2661,16 @@ static irqreturn_t i965_irq_handler(DRM_IRQ_ARGS)
 			intel_prepare_page_flip(dev, 1);
 
 		for_each_pipe(pipe) {
-			if (pipe_stats[pipe] & PIPE_START_VBLANK_INTERRUPT_STATUS &&
-			    drm_handle_vblank(dev, pipe)) {
+			if (pipe_stats[pipe] & PIPE_START_VBLANK_INTERRUPT_STATUS) {
 				i915_pageflip_stall_check(dev, pipe);
 				intel_finish_page_flip(dev, pipe);
+				drm_handle_vblank(dev, pipe);
 			}
 
 			if (pipe_stats[pipe] & PIPE_LEGACY_BLC_EVENT_STATUS)
 				blc_event = true;
 		}
 
-
 		if (blc_event || (iir & I915_ASLE_INTERRUPT))
 			intel_opregion_asle_intr(dev);
 
-- 
1.7.10.4